1. Field of the Invention
Aspects of the present invention relate to a method for preparing a lithium manganese oxide positive active material for a lithium ion secondary battery. More particularly, aspects of the present invention relate to a method for preparing a lithium manganese oxide positive active material for a lithium ion secondary battery, which has spherical spinel-type lithium manganese oxide particles having two or more different types of sizes, a lithium manganese oxide positive active material prepared thereby, and a lithium ion secondary battery including the same.
2. Description of the Related Art
Due to recent trends toward more compact and lighter portable electronic equipment, such as cellular phones, camcorders and notebook computers, there has been a growing demand for improving characteristics of lithium ion secondary batteries, including high performance, durability and reliability, which can be used as power sources for the electronic equipment. In addition, as much attention has been paid to achieving electromotive vehicles, lithium ion secondary batteries are drawing particular attention as power sources for the electromotive vehicles.
A lithium ion secondary battery generally includes a positive electrode and a negative electrode that are capable of intercalating and deintercalating lithium ion, a separator that prevents the positive electrode and the negative electrode from physically contacting each other, and an organic electrolyte or polymer electrolyte that transmits lithium ion between the positive and negative electrodes. In the lithium ion secondary battery, when lithium ion is intercalated/deintercalated in the positive electrode and the negative electrode, electrical energy is generated through an electrochemical oxidation/reduction reaction.
Carbon materials of various kinds may be used as a negative active material of a lithium ion secondary battery and lithium metal oxide such as LiCoO2, LiMnO2, or LiMn2O4 may be used.
Among lithium metal oxides, spinel-type lithium manganese oxide is an environmentally friendly and safe positive active material because detrimental heavy metal like cobalt is not used. Thus, the spinel-type lithium manganese oxide is advantageously used for power storage of electromotive vehicles or the like.
However, the spinel-type lithium manganese oxide is disadvantageous in that it has low energy density per weight and volume compared to laminar-type lithium metal oxide.